The present invention relates to methods for making and treating contact lenses and methods for reprocessing fluids used in treating contact lenses. More particularly the invention relates to methods for making and treating contact lenses to remove undesirable extractable materials from the contact lenses prior to packaging the lenses and prior to use of the lenses by an individual, and to methods for reprocessing, for example, for reuse, fluid materials, such as extraction media, aqueous media and the like, used in the treatment of contact lenses.
Contact lenses, particularly newly molded contact lenses, often are processed using one or more fluids, for example, liquids to remove undesirable components from the lenses prior to packaging of the lenses. To illustrate, newly formed polymeric contact lenses, such as silicone hydrogel contact lenses or contact lenses which comprise a silicone hydrogel material, often contain unreacted monomers which are removed by extracting the monomers from the lenses with a liquid medium, such as a non-aqueous liquid medium or an organic solvent. After the extraction processing, the contact lens is contacted with an aqueous liquid medium to hydrate the lens, for example, to swell the lens with water.
During such fluid processing, relatively large amounts of fluids, such as solvents, are used and are discarded. This represents a substantial cost in contact lens manufacturing. In addition, discarding or disposing of such large amounts of solvents can be an environmental concern and present risks to people handling the solvents and involved in the extraction processes.
In addition, contact lenses including hydrophilic polymeric materials are often subjected to elevated temperatures, for example, during sterilizing, packaging, cleaning, disinfecting and the like processing. Such elevated temperatures may result in damage, for example, discoloring, weakening and/or other damage and the like, to the contact lenses.
Thus, there remains a need for systems and methods which effectively extract undesirable components, such as unreacted monomers, from the contact lenses, such as silicone hydrogel contact lenses, and hydrate such extracted contact lenses, and which are cost effective and safe to use. There also remains a need for systems and methods to enhance the heat stability of the contact lenses or lens materials to reduce deleterious effects of elevated temperatures to which such lenses are exposed.